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1、MetabolismofGlycogenCharpter18Harper’sillustratedbiochemistry26thedition1.Introductionandbiomedicalimportance2.Glycogenbiosynthesis(glycogenesis)3.Glycogenolysis4.CyclicAMPintegratestheregulationofglycogenolysisandglycogenesisIntroduction(1).WhatisGlycogen?Glycogenis

2、themajorstoragecarbohydrateinanimals,correspondingtostarchinplants.Itisabranchedpolymerofα–D-glucose.Itoccursmainlyinliverandmuscle(2)MetabolismofGlycogencontainsGlycogenesisandGlycogenolysisGlycogenesisoccursmainlyinmuscleandliver.Glycogenolysisisnotthereverseofglycog

3、enesisbutisaseparatepathway.*Muscleglycogenisareadilyavailablesourceofglucoseforglycolysiswithinthemuscleitself.*Liverglycogenfunctionstostoreandexportglucosetomaintainbloodglucosebetweenmeals.Itcanbeused8-12hoursafterfasting.biomedicalimportanceGlycogenstoragediseases

4、areagroupofinheriteddisorderscharacterizedbydeficientmobilizationofglycogenordepositionofabnormalformsofglycogen,leadingtomuscularweaknessorevendeath.2.Glycogenbiosynthesis(glycogenesis)1.概念2.合成部位肝、肌肉和肾3.过程(1)glucoseglucose6-phosphate,hexokinaseglucokinase2.Glycogenbio

5、synthesis(glycogenesis)2.Glucose6-phosphate3:Synthesisaspecialnucleotideofglucose(uridinediphosphateglucose,UDPGlc).Glucose1-phosphatephosphoglucomutase酶：尿苷二磷酸葡萄糖焦磷酸化酶UDPGlcpyrophosphorylaseUDPG“活性的葡萄糖”UDPG“活性的葡萄糖”4:Glycogensynthasecatalyzestheformationofaglycosidebond

6、.5:Branchinginvolvesdetachmentofexistingglycogenchains.Biosynthesisofglycogenglycogenprimer3.GlycogenolysisGlycogenolysisisnotthereverseofglycogenesisbutisaseparatepathway.(1)Glycogenphosphorylasecatalyzesyieldglucose1-phosphate.Glucose-6-phosphate(2)glucose6-phosphate

7、canbeformedfromglucose1-phosphate.glucose1-phosphate.phosphoglucomutase(3)Inliverandkidneyglucose-6-phosphataseglucose6-phosphateglucoseglucosethatisexported,leadingtoanincreaseinthebloodglucoseconcentration.Inmuscle,thereisNOTglucose-6-phosphatase(4)Hydrolysisofthe1→6

8、linkagesrequiresthedebranchingenzymeformsfreeglucose.糖原分解与合成的主要步骤及限速酶4.RegulationofglycogenmetabolismItiseffectedbyab